I honestly have not been a fan of all-in-one form factor PCs because simply they are too proprietary and not user serviceable. While yes, the Z1 still has many proprietary parts like motherboard and power supply, adding in user serviceability and more "standard" hardware makes this thing an absolute win.
We are very excited to see the new HP Z1 workstations, not just because of the push towards a more business-class all-in-one, but to be pushing the envelope in performance and capabilities in an all-in-one form factor like this, and especially at a decent price once you consider that most 27" IPS displays alone are around $1,000!
I have not heard yet if the HP Z1 will support touch input. Even if it does, I do not imagine it will be highly accurate like a wacom tablet or anything, but more to the likes of the standard Touchsmart capabilities of previous HP all-in-one displays. After all, if it did have a highly accurate and pressure sensitive touch input like a cintiq or wacom tablet, then it would probably be much more than the suggested price!